The Doctor and Ace in “Dragonfire”

Ace! Where d'you think you're going?

Ace

[miserable] Perivale...

Ah yes, but by which route? The direct route with Glitz? Or the scenic route? [Ace begins to smile] Well, do you fancy a quick trip around the twelve galaxies and then back to Perivale in time for tea?

Ace

[jumps for joy] ACE!

[suddenly stern, he holds up three fingers] But there are three rules! One: I'm in charge.

Ace

Whatever you say, Professor!

[holding up two fingers] Two: I'm not 'the Professor', I'm the Doctor!

Ace

Whatever you want!

And the third... [he suddenly smiles] Well, I'll think up the third by the time we get back to Perivale. [they smile at each other]